You have already solved real-world problems using the percent equations. (Lesson 7–5)

• Find percent of increase and decrease.

• Solve real-world problems involving markup and discount.

If the answer is positive, the percent of change is an increase.

If the answer is negative, the percent of change is a decrease.

Find the Percent of Change

Find the percent of change from 20 students to 24 students. State whether the percent of change is an increase or decrease.

Step 1 Subtract to find the amount of change.

24 – 20 = 4 final amount – original amount

Step 2 Write a ratio that compares the amount ofchange to the original amount. Express theratio as a percent.

Find the Percent of Change

Cross multiply.

Answer: 20%; increase

Step 3 The percent of change is positive, so it is a percent of increase.

4 • 100 = 20 • x

20% = x Divide.

A. –20%; decrease

B. –25%; decrease

C. 20%; increase

D. 25%; increase

What is the percent of change from 24 to 30 students?

A. –17.9%; decrease

B. –21.7%; decrease

C. 17.9%; increase

D. 21.7%; increase

John had $420 in his checking account at the beginning of May. At the beginning of June he had $345. What was the percent of increase or decrease to the nearest tenth?